Advocates have succeeded in obtaining a temporary restraining order preventing the re-opening of horse slaughter plants on American soil, just days before at least one abattoir was planning to reopen.

A federal court has issued a temporary restraining order to halt US Department of Agriculture (USDA) inspections of horse slaughter plants, which effectively prevents any plant from opening in the US.

Front Range Equine Rescue, the Humane Society of the United States (HSUS), and other horse advocates filed suit against the USDA last month, saying the agency failed to conduct the required environmental review before agreeing to place inspectors in horse slaughter plants.

The injunction will remain in place for 30 days, at which time the court will decide whether to extend the order.

“We’ve won a temporary but life-saving reprieve for horses, and it’s good news indeed that the kill boxes in New Mexico and Iowa will be empty of horses in the weeks ahead,” HSUS president and chief executive Wayne Pacelle said.

“We’ll continue to make arguments when our case resumes in a month that these plants cannot legally operate because of inadequate environmental review.”

The hearing was held on August 2 in New Mexico, and was the last major hurdle remaining in the way of horse slaughter plants opening in the US for the first time in six years.

The Valley Meat Company plant in Roswell, New Mexico, and Responsible Transportation’s plant in Sigourney, Iowa, were reportedly set to open within days.

The USDA had issued a so-called “grant of inspection” to each of the plants, saying it was required by law to grant the inspections if all federal requirements were met. It said it was obliged to assign meat inspectors to the plants.

The Foundation to Protect New Mexico Wildlife, founded by former New Mexico governor Bill Richardson and legendary actor and director Robert Redford, applauded the court ruling.

The foundation had joined the list of plaintiffs seeking the restraining order.

“This is a huge victory for those of us who adamantly oppose horse slaughter, the animals that we are working so hard to protect, and the environment,” Richardson said.

“However, this fight isn’t over. The Foundation to Protect New Mexico Wildlife will continue to seek an all-out federal ban on horse slaughter, as well as urge officials to find new horse rescue and retirement solutions.”